WO2006019067A1

WO2006019067A1 - Optical pickup/lens drive device and method

Info

Publication number: WO2006019067A1
Application number: PCT/JP2005/014898
Authority: WO
Inventors: Takehiro Matsuda; Takeshi Hamada; Katsuhiko Tanimoto
Original assignee: Pioneer Corporation
Priority date: 2004-08-20
Filing date: 2005-08-15
Publication date: 2006-02-23
Also published as: JPWO2006019067A1

Abstract

An optical pickup/lens drive device and method which are capable of reducing a correction time and whose structures are simplified. An optical pickup/lens drive device (31) comprises a light source emitting laser light, an actuator (53) including an objective lens (15) for condensing the laser light on an information recording surface of an optical disc D, and a mechanism (36) placed between the light source and the actuator (53) and correcting spherical aberration of the laser light as converging light or diverging light. The aberration correcting mechanism (36) comprises a first aberration correcting mechanism (34) for performing an interlayer thickness correction of the information recording surface, and a second aberration correcting mechanism (35) for performing an in-layer thickness correction of the information recording surface.

Description

Optical pickup lens driving apparatus and method

Technical field

[0001] The present invention relates to an optical pickup lens driving apparatus and method.

Background art

Conventionally, optical memory technology that uses optical disks with pit-like patterns as high-density and large-capacity storage media has been used for Digital Versatile Disks (DVDs), video disks, document file disks, and data files. It has been put into practical use while expanding. In such a high-density 'large-capacity optical disc, it is necessary to correct spherical aberration in order to perform optical disc substrate thickness error correction (intra-layer error correction) and multilayer disc inter-layer thickness correction (inter-layer correction). However, a method of correcting spherical aberration by moving the lens along the optical axis direction (for example, see Patent Document 1) or a method of correcting spherical aberration by generating spherical aberration with a liquid crystal element (for example, Patent Document 2). Have been implemented).

[0003] For example, the conventional optical pickup / lens driving device 1 shown in FIG. 1 is not shown! An objective lens 15 for condensing and irradiating light emitted from a light source on an information recording surface of an optical disc D; An aberration correction mechanism 4 that is disposed between the light source and the objective lens 15 and corrects spherical aberration using the light as convergent light or divergent light.

In the case of the aberration correction mechanism 4, a pair of lens groups including the positive lens 2 and the negative lens 3 are accommodated in the movable lens holder 6 and the fixed lens holder 7, respectively.

The negative lens 3 is housed in the fixed lens holder 7 and fixed to the optical pickup body 9, and the positive lens 2 is supported so as to be movable in the optical axis direction with respect to the fixed lens holder 7. The movable lens holder 6 is accommodated.

Then, the movable lens holder 6 housing the positive lens 2 is moved along the optical axis direction by a predetermined amount by the stepping motor 10 and the lead screw feed mechanism 11.

Further, the conventional spherical aberration correction mechanism 21 shown in FIG. 2 is a conventional example in the case of correcting the spherical aberration only by the liquid crystal element 23.

As shown in Fig. 2, the objective lens 15 and the liquid crystal element 23 for correcting spherical aberration move together. Thus, both are mounted on the lens holder 26 in the same actuator 25. This is because when the liquid crystal element 23 generates a large spherical aberration such as inter-layer correction, if the center of the liquid crystal element 23 and the objective lens 15 is misaligned, the light emitted from the objective lens 15 is also subject to coma aberration. Behaves like

In other words, if the liquid crystal element 23 is not mounted on the actuator 25 and is fixed to the pickup base 28 together with other optical components, the actuator 25 and the objective lens 15 follow the eccentricity of the optical disk. Since it shifts in the tracking direction (disk radial direction) in units of 100 m, the read / write performance of the optical disk deteriorates significantly with a double punch that impairs the ability to correct spherical aberration and deteriorates coma.

Accordingly, the objective lens 15 and the liquid crystal element 23 for correcting spherical aberration are both mounted on a lens holder 26 which is a movable part of the same actuator 25 so as to move together.

[0007] Patent Document 1: JP 2004-152426 A

Patent Document 2: Japanese Patent Laid-Open No. 2000-57616

Disclosure of the invention

Problems to be solved by the invention

[0008] By the way, in the aberration correction mechanism 4 for correcting the spherical aberration by the stepping motor type expander as shown in FIG. 1, the sensitivity (lead angle) easy to correct minimizes the aberration correction amount per motor rotation. Designed as

Therefore, in order to correct the interlayer thickness between the upper layer dl and the lower layer d2 on the information recording surface of the optical disc D, a larger amount of aberration correction is required than in each of the upper layer dl and the lower layer d2, so that correction is required. The time is very long (for example, about 4 times the error in the layer chasing from the center of each layer).

In addition, the stepping motor type expander (lens driving mechanism) of the aberration correction mechanism 4 needs to be adjusted and fixed at a place (pickup base) integrated with other optical components of the optical pickup. If the size of the optical pickup is to be realized, the required size of the final optical pickup is small, and the stepping motor 10 is limited in size.

Therefore, the motor that can be selected realistically has a limit in torque, and the focus jump Time force more than 10 times The problem of inter-layer spherical aberration correction is an example.

[0010] Further, the small and high-performance stepping motor 10 as described above is expensive, and a large stepping motor type expander has a problem that the power consumption of the drive increases when the heavy optical pickup becomes heavy. . In addition, if the optical pickup becomes heavy, there is a problem that the time for searching becomes longer.

On the other hand, since the spherical aberration correction mechanism 21 using only the liquid crystal element 23 as shown in FIG. 2 is weak against the misalignment with the objective lens 15 as described above, the same actuator 25 as the objective lens 15 is used. It is necessary to adjust and fix the liquid crystal element 23 to the lens holder 26 as well. In general, a liquid crystal element 23 as an aberration correction element used in an optical pickup is sandwiched between two thin glass plates and weighs several tens of mg.

This is a fatal weight for the actuator 25. For example, there is a problem that the sensitivity is insufficient and the high-speed speed cannot be dealt with, or the recording / reproducing ability of a bad disk is lowered.

[0012] Normally, when the two-axis actuator for the objective lens 15 is realized by a moving coil type, it has two circuits of a focus coil and a tracking coil. It is used to energize the drive coil, and a separate connection means is required to supply power to the liquid crystal element 23.

This significantly reduces productivity, and is a factor that deteriorates the lens tilt of the objective lens 15 (actuator drive unit tilt) when displaced in the focus and tracking directions, which are the basic characteristics of a biaxial actuator. Become. An example of the problem is that coma aberration occurs when the objective lens 15 is tilted, and the recording / reproducing ability of the optical disk is reduced.

[0013] Also, if a moving two-axis actuator is realized with a magnet type, it is difficult to achieve high sensitivity because the magnet is originally placed on the movable part. One example is the problem of carrying heavy loads and being unable to increase the sensitivity further, which is disadvantageous for high speed.

In addition, in order to correct a large amount of spherical aberration, the liquid crystal layer of the liquid crystal element 23 needs to be thick, so that the time required for interlayer correction becomes long as an example. Means for solving the problem

The invention according to claim 1 is an optical pickup lens drive comprising: a light source that emits laser light; and an actuator that includes an objective lens that focuses the laser light on a recording surface of a recording medium. The apparatus further includes a first aberration correction mechanism, and an aberration correction amount force and a second aberration correction mechanism from the first aberration correction mechanism.

The invention according to claim 6 condenses the laser light on the recording surface of the recording medium when condensing the focal position of the laser light emitted from the light source on each of the plurality of information recording layers of the recording medium. A focus moving step in which an actuator including an objective lens for moving the focus position of the laser beam to focus jump to each of the information recording layers, and a first aberration correction mechanism moves the focus of the laser light between the layers of the information recording layer An interlayer correction step for performing correction corresponding to the thickness; and an intra-layer correction step for correcting the focal point of the laser beam according to the thickness of the information recording layer by the second aberration correction mechanism.

Brief Description of Drawings

FIG. 1 is a schematic configuration diagram illustrating a conventional optical pickup lens driving device.

FIG. 2 is a top perspective view and a bottom perspective view of an actuator provided with a conventional spherical aberration correction mechanism.

FIG. 3 is a schematic configuration diagram of an optical pickup lens driving device according to an embodiment of the present invention.

4 is an upper perspective view of the first aberration correction mechanism shown in FIG.

5 is a top perspective view and a bottom perspective view of the first aberration correction mechanism 34 shown in FIG. 3. FIG.

6 is a perspective view of the second aberration correction mechanism 35 shown in FIG.

FIG. 7 is an explanatory diagram showing interlayer correction and intra-layer correction error in a dual-layer disc.

FIG. 8 is a schematic diagram for explaining an operation of correcting an error in spherical aberration between layers and between layers by the optical pickup lens driving device shown in FIG. 3.

FIG. 9 is a schematic diagram for explaining an operation for correcting an error of spherical convergence between layers and between layers by the optical pickup lens driving device shown in FIG. 3.

FIG. 10 is a schematic diagram for explaining an operation for correcting an error of spherical aberration between layers and between layers by the optical pickup / lens driving device shown in FIG. 3. Ο

FIG. 11 is a schematic diagram for explaining an operation of correcting an error of spherical convergence 1-difference between layers and between layers by the optical pickup / lens driving device shown in FIG. 3.

Explanation of symbols

Objective lens

31 Optical pickupLens drive device

32 Movable lens

33 Fixed lens

34 First aberration correction mechanism

35 Second aberration correction mechanism

37 Stutsuba

38 Fixed lens holder

40 Lens drive mechanism

42 Movable lens Honoreda

50 motor

53 Actuator

60 Liquid crystal elements

BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment of an optical pickup lens driving apparatus and method according to the present invention will be described.

An optical pickup lens driving device according to the present invention includes a light source that emits laser light and an actuator that includes an objective lens that focuses the laser light on a recording surface of a recording medium. In addition, it further includes a first aberration correction mechanism and a second aberration correction mechanism having a smaller aberration correction amount than the first aberration correction mechanism.

[0019] The recording medium has a plurality of information recording layers, and the actuator has a focus jump control means for moving the focal position of the laser beam to each of the information recording layers, and the first aberration correction mechanism Performs correction corresponding to the interlayer thickness of the information recording layer, and the second aberration correction mechanism performs correction corresponding to the thickness in the layer. The first aberration correction mechanism includes a movable lens that is controlled to move in the optical axis direction and the movable lens. A lens driving mechanism for moving the lens in accordance with the thickness of the information recording layer.

Further, the lens driving mechanism force includes a movable lens holder that accommodates the movable lens and is movable in the optical axis direction, and has a stagger portion that regulates a range of movement of the movable lens holder between predetermined positions. .

In the case of the present invention, the lens driving mechanism for correcting the interlayer thickness of the information recording surface can be smaller than a conventional stepping motor type expander or can be realized by a switching mechanism using a normal motor. One aberration correction mechanism can be miniaturized, and thereby the optical pickup can be miniaturized. Moreover, since an expensive stepping motor is not used for the lens drive mechanism in the first aberration correction mechanism, and the mechanism can be simplified, even if a liquid crystal element is introduced into the second aberration correction mechanism, it is still possible to reduce the cost. it can.

In addition, the second aberration correction mechanism includes a liquid crystal element that generates a spherical aberration corresponding to the inner thickness of the information recording surface.

In this case, since the liquid crystal element in the second aberration correction mechanism has a small amount of spherical aberration to be corrected, the coma caused by the misalignment is within an allowable range, and other optical components that do not need to be driven integrally with the objective lens. Productivity is remarkably improved because it only needs to be adjusted and fixed in the same place. In addition, since it is not necessary to drive the objective lens and the liquid crystal element in the second aberration correction mechanism integrally with the objective lens, the optical pickup can be thinned and the optical pickup can be reduced along with the downsizing of the first convergence correction mechanism. It can be made smaller and thinner, opening up the path to slim high-density drives.

[0022] Here, the interlayer thickness means the distance between the recording layers of a disc having a plurality of recording layers, and the in-layer thickness error is a discrepancy in the in-layer thickness inherent to the disc caused by a manufacturing error, for example. means. Here, the thickness in the layer means the thickness of the recording layer, and the error in the thickness in the layer means a variation in the thickness of the recording layer inherent to the disc caused by a manufacturing error as described above.

The optical pickup lens driving method of the present invention collects the laser beam on the recording surface of the recording medium when condensing the focal position of the laser beam emitted from the light source on each of the plurality of information recording layers of the recording medium. An actuator including a light objective lens determines the focal position of the laser beam. A focus movement step for moving each information recording layer by performing a focus jump; an interlayer correction step in which the first aberration correction mechanism corrects the focal point of the laser beam in accordance with the interlayer thickness of the information recording layer; An aberration correction mechanism comprising: an intra-layer correction step for correcting the focal point of the laser beam in accordance with the inner thickness of the information recording layer.

Example

Hereinafter, an optical pickup lens driving device according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 3 is a schematic configuration diagram of an optical pickup lens driving device 31 according to an embodiment of the present invention. FIGS. 4 and 5 are a top perspective view and a bottom oblique view of the first aberration correction mechanism 34 shown in FIG. FIG. 6 is a perspective view of the second aberration correction mechanism 35 shown in FIG.

As shown in FIG. 3, the optical pickup lens driving device 31 of the present embodiment condenses the light source (not shown) that emits the laser light and the information recording surface of the optical disc D. An actuator 53 including an objective lens 15, and an aberration correction mechanism 36 that is disposed between the light source and the actuator 53 and corrects spherical aberration by using the laser light as convergent light or divergent light.

The aberration correction mechanism 36 includes a first aberration correction mechanism 34 that performs interlayer thickness correction between the upper layer dl and the lower layer d 2 on the information recording surface of the optical disc D, and the upper layer dl and the upper layer dl on the information recording surface of the optical disc D. A second aberration correction mechanism 35 that corrects an in-layer thickness error of the lower layer d2.

Further, the first aberration correction mechanism 34 includes a movable lens 32 that is controlled to move in the optical axis direction with respect to the fixed lens 33, as shown in FIGS. An aberration correction lens group that corrects spherical aberration by moving light into a convergent light or divergent light, and the movable lens 32 as an interlayer thickness (interlayer gap) between the upper layer dl and the lower layer d2 on the information recording surface of the optical disc D. A lens driving mechanism 40 that moves correspondingly.

The lens driving mechanism 40 further includes a fixed-side lens holder 38 that houses the fixed lens 33 and a movable lens 32 that is movable in the optical axis direction with respect to the fixed-side lens holder 38. A movable lens holder 42, and a motor 50 for moving the movable lens holder 42. The fixed-side lens holder 38 fixed to the pickup body includes a pair of guide shafts 39 and 39 for slidingly guiding the movable-side lens holder 42. The fixed-side lens holder 38 is engaged with the body portion 41 and the engaging portion of the movable-side lens holder 42. 44 are slidably guided by guide shafts 39 and 39, respectively.

Further, in the fixed side lens holder 38, the both end support portions of one guide shaft 39 to which the main body portion 41 of the movable side lens holder 42 is slidably guided contacts the both end surfaces of the main body portion 41. Thus, the movable side lens holder 42 has a pair of stopper portions 37 and 37 for restricting the movement range between two positions.

The main body 41 of the movable lens holder 42 is provided with an arm engaging portion 45 that engages with an engaging protrusion 51 that protrudes from the tip of the swing arm 52 of the motor 50.

Therefore, when the motor 50 is driven and the swing arm 52 swings, the movable lens holder 42 is driven by the main body 41 via the arm engaging portion 45, and both end surfaces of the main body 41 are respectively driven. Force S Move between two positions within the range where it abuts against the stoppers 37 and 37 and is mechanically stopped. That is, the first aberration correction mechanism 34 of the present embodiment has the fixed lens 33 and the movable lens corresponding to the moving distance to the lens driving mechanism 40 that moves back and forth between two positions where the movable lens holder 42 can be mechanically stopped. Depending on the lens distance to 32, a set of lenses capable of generating spherical aberration is incorporated.

[0031] The spherical aberration generated at each position is approximately halfway between the upper layer dl and lower layer d2 to be corrected (design center) as shown in Fig. 7 (interlayer correction and intralayer correction error in a two-layer disc). The lens group is designed to match the correction value (interlayer gap T) of die, d2c).

Note that the first aberration correction mechanism 34 of the above embodiment shares the interlayer correction in FIG. 7, and the final spherical aberration target value is finely adjusted by the first aberration correction mechanism 35 described later. Therefore, it is sufficient that the movable lens 32 can move back and forth between the center dies and d2c of the upper layer dl and the lower layer d2 shown in FIG. That is, the movable lens 32 and the fixed lens 33 that are the constituent lenses of the lens group may be realized by a spherical lens. Since aspherical lenses are expensive, there is no surplus if they are realized with spherical lenses.

In addition, the second aberration compensation provided between the first aberration correction mechanism 34 and the actuator 53 is also provided. As shown in FIG. 6, the positive mechanism 35 includes a liquid crystal element 60 that generates spherical aberration corresponding to the layer thickness errors tl and t2 of the upper layer dl and the lower layer d2 of the information recording surface.

A spherical aberration correction element represented by a liquid crystal element 60 as shown in FIG. 6 receives a voltage corresponding to a spherical aberration suitable for the required layer thickness error tl, t2 as a spherical aberration correction signal, and drives the liquid crystal. Thus, a desired spherical aberration is generated.

In this case, since the liquid crystal element 60 in the second aberration correction mechanism 35 has a small amount of spherical aberration to be corrected, the coma generated by the misalignment is within an allowable range and is driven integrally with the objective lens 15 of the actuator 53. It can be adjusted and fixed in the same place as other optical components.

In addition, since it is not necessary to drive the liquid crystal element 60 in the second aberration correction mechanism 35 integrally with the objective lens 15 driven by the focus coil 55 of the actuator 53! With the downsizing of the aberration correction mechanism 34, the optical pickup can be made smaller and thinner, opening the way to a slim high-density drive.

That is, by performing the substrate thickness error correction (intra-layer error correction) of the optical disc D and the interlayer thickness correction (inter-layer correction) of the multilayer disc by separate first and second aberration correction mechanisms 34 and 35, respectively. Thus, the correction time can be shortened, the configuration of the aberration correction mechanism 36 can be simplified, and the overall low cost can be achieved.

Next, an error of spherical aberration in the interlayer and in the layer is detected by the optical pickup lens driving device 31 including the first aberration correction mechanism 34 and the second aberration correction mechanism 35 of the above-described embodiment. The outline of the operation of correcting the above and obtaining the disc information reading signal with high quality will be described. As shown in Fig. 8, the micro spot (focus) that focused the laser light from the light source initially accessed the upper layer dl of the optical disk D, and accessed the lower layer d2 (read / write) as shown in Fig. 9. First, the first aberration correction mechanism 34 is driven to operate to the position of the desired lower layer d2, and spherical aberration correction corresponding to the lower layer d2 to be moved is performed (interlayer correction step). .

Next, as shown in FIG. 10, an actuator 53 having a focus jump control means drives the objective lens 15 by a kick pulse to perform a focus jump, and moves a minute spot to the destination layer (focus movement step). ). Then, the liquid crystal element 60 of the second aberration correction mechanism 35 is driven to correct the in-layer error in the lower layer d2 based on the information on the optical disk D force as shown in FIG. 11 (in-layer correction step), Read Z write operation is started by optical pickup.

In addition, when the intra-layer error correction servo is always applied based on the information from the optical disc D, the intra-layer error correction by the second aberration correction mechanism 35 and the read / write operation by the optical pickup are operated in parallel.

That is, the first aberration correction mechanism 34 in the optical pickup lens driving device 31 of the present embodiment is smaller than the stepping motor type expander of the conventional aberration correction mechanism 4 shown in FIG. The bi-aberration correction mechanism 35 can be made thinner than the conventional liquid crystal element.

Further, the second aberration correction mechanism 35 of this embodiment does not need to be integrated with the objective lens 15 of the actuator 53.

In this case, the lens driving mechanism 40 for correcting the interlayer thickness of the information recording surface is smaller than the conventional stepping motor type expander, and the optical pickup can be miniaturized. In addition, an expensive stepping motor is not used for the lens drive mechanism 40 in the first aberration correction mechanism 34, and a simple switching mechanism using the normal motor 50 can be used, so the liquid crystal element 60 is introduced into the second aberration correction mechanism 35. Even so, it is still cheap.

In addition, the overall operation can be significantly speeded up compared to the case where the interlayer thickness is corrected only by the liquid crystal element.

[0040] The configurations of the first aberration correction mechanism, the second convergence correction mechanism, the lens drive mechanism, the fixed lens holder, the movable lens holder, the actuator, etc. in the optical pickup lens driving device of the present invention are as described above. Needless to say, the present invention is not limited to the configuration of the embodiments, and various forms can be adopted based on the gist of the present invention.

This application is based on a Japanese patent application filed on August 20, 2004 (Japanese Patent Application No. 2004-241409), the contents of which are incorporated herein by reference.

Claims

The scope of the claims

[1] a light source that emits laser light;

An optical pickup lens driving device comprising: an actuator including an objective lens for condensing the laser beam on a recording surface of a recording medium,

An optical pickup lens driving device, further comprising: a first aberration correction mechanism; an aberration correction amount smaller than that of the first aberration correction mechanism; and a second aberration correction mechanism.

[2] The recording medium has a plurality of information recording layers,

The actuator has a focus jump control means for moving the focal position of the laser beam to each information recording layer,

The first aberration correction mechanism corrects the focal point of the laser beam in accordance with the thickness of the information recording layer, and the second aberration correction mechanism corrects in accordance with the thickness of the layer. Item 1. The optical pickup lens driving device according to Item 1.

[3] The first aberration correction mechanism includes a movable lens that is controlled to move in the optical axis direction;

3. The optical pickup lens driving device according to claim 2, further comprising a lens driving mechanism that moves the movable lens in accordance with an interlayer thickness of the information recording layer.

4. The optical pick-up according to claim 1, wherein the second aberration correction mechanism includes a liquid crystal element that generates a spherical aberration corresponding to an inner thickness of the information recording layer. · Lens drive device.

[5] The lens drive mechanism includes a movable lens holder that accommodates the movable lens and is movable in the optical axis direction, and controls a moving range between predetermined positions of the movable lens holder. 4. The optical pickup lens driving device according to claim 3, further comprising:

[6] When condensing the focal position of the laser beam emitted from the light source on each of the plurality of information recording layers of the recording medium,

An actuator including an objective lens for condensing the laser light on a recording surface of a recording medium; a focus moving step of moving the focal position of the laser light by focus jumping to each of the information recording layers;

The first aberration correction mechanism corresponds the focal point of the laser beam to the interlayer thickness of the information recording layer. An interlayer correction step for performing correction, and

An intra-layer correction step in which a second aberration correction mechanism corrects the focal point of the laser beam in accordance with the thickness of the information recording layer;

Optical pickup with lens driving method.